China defends poultry vaccination policy in wake of killer virus

HONG KONG — China's Agriculture Ministry issued a strongly worded defense late Friday afternoon of its policy of large-scale vaccination of poultry against the H5N1 avian influenza virus over the last decade, saying it was not interfering with its efforts now to identify the emerging H7N9 virus.

Dr. Alex Thiermann, president of the standard-setting Code Commission of the World Organization for Animal Health, had expressed concern this week that vaccination against the earlier bird flu strain might have made it harder this spring for Chinese veterinary technicians to spot the recent spread of the H7N9 virus.

The new bird flu strain has sickened 40 people and killed 11 in recent weeks in Shanghai and three nearby provinces, including two more cases and one more death confirmed Friday.

Thiermann reiterated his organization's long-standing support for poultry culling as a way to fight outbreaks of disease while preserving the ability to test surviving poultry reliably for disease.

Culls involve euthanizing not only infected poultry, but also all poultry in a radius that can extend several miles around each site of infection.

In a statement Friday in response to questions submitted by fax Wednesday, the Agriculture Ministry said tests for the two viruses were different.

“Vaccinating poultry against H5N1 on a large scale does not make it harder to identify H7N9 in poultry,” the statement said, adding that vaccination had been an effective way to greatly reduce the incidence of H5N1 in recent years.

The statement did not address a separate question about whether the Agriculture Ministry had been testing only for H5N1 in recent years or had also tested for other avian influenza viruses.

Virologists at Hong Kong University, which has the best-known center for research on avian influenza in China, disagree among themselves on whether China's practice of distributing free H5N1 vaccines to millions of farmers has made it harder to detect H7N9.

The World Organization for Animal Health, based in Paris, issued a separate statement late Thursday in which it endorsed humane culls at infected farms but also said a supplemental policy “could be to apply a suitably adapted vaccination policy of limited duration.”

Farmers in China have strongly opposed culls, fearing the loss of valuable poultry.